Alicin Nagle, an in-charge auditor, is reviving the inventory controls for the city of Carlton's vehicle maintenance facility. Nagle has learned the following:

a. Vehicle maintenance records indicate that, even though the total number of trucks is decreasing, the number of inoperative trucks waiting for spare parts is increasing.

b. Stockroom employees have been unable to find some parts, even though the perpetual inventory system shows the parts on hand.

c. The investment in spare parts inventory has remained at about the same level in each of the last three years.

d. Many of the spare parts can be used for passenger cars.

e. A clerk in the parts warehouse office maintains the perpetual inventory records.

Required: 

Design tests of controls for each item listed.